1. Field of the Invention
The present invention relates generally to heating units, erasing devices, and information erasing and recording apparatuses and, more specifically, to a heating unit that heats a heat-sensitive recording medium, an erasing device that erases information recorded on a heat-sensitive recording medium, and an information erasing and recording apparatus that erases and records information from and on a heat-sensitive recording medium.
2. Description of the Related Art
In recent years and continuing to the present, attention is being given to a reversible heat-sensitive recording medium (hereinafter referred to as a heat-sensitive recording medium), on and from which information can be repeatedly recorded and erased, from the viewpoint of protecting the environment and recycling. A heat-sensitive recording medium (see Patent Document 1) capable of reversibly assuming transparent and cloudy states using light scattering variations of a polymer membrane in which organic low molecular crystal particles are dispersed and another heat-sensitive recording medium (see Patent Document 2) having a recording layer coated with a leuco dye capable of reversibly assuming color optical and erasing states are recording media on and from which information can be recorded and erased by applying proper heat to the recording media to make the recording layers relatively colored or decolored.
In order to record information on a heat-sensitive recording medium, it is necessary to erase the previous information recorded on the heat-sensitive recording medium in advance. Therefore, in a thermal printer or the like, the heat-sensitive recording medium is generally heated by a substrate (hereinafter referred to as a ceramic substrate) made, for example, of a ceramic having low heat conductivity and a thermal head having a heating element formed on the surface of the substrate so that the previous information is erased in advance. However, because the ceramic substrate is more fragile than metals, etc., it is difficult to fix the ceramic substrate to equipment or the like using screws or bolts. For this reason, the thermal head attached to a thermal printer is held with the entire surface on one side of the ceramic substrate bonded on a base made of metals, heat-resistant resins, or the like. As a result, heat is disadvantageously transferred from the ceramic substrate to the base through an adhesive layer, so that it is necessary to use a heat-resistant adhesive. Moreover, where the ceramic substrate and the base have different thermal expansion coefficients, it is foreseen that aging degradation such as poor bonding and breakage of the ceramic substrate may occur over time due to the repetitive stopping operations of the apparatus or the like.    Patent Document 1: JP-A-55-154198    Patent Document 2: JP-A-5-124360